05000254/LER-2024-001, Nuclear Power Station, Unit 1, Technical Specification 3.5.2 Action Not Performed Due to Inadequate Procedure Adherence
| ML25021A090 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/21/2025 |
| From: | Hild D Constellation Energy Generation |
| To: | Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| SVP-25-005 LER 2024-001-00 | |
| Download: ML25021A090 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2542024001R00 - NRC Website | |
text
Constellation,.
SVP-25-005 January 21, 2025 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station, Unit 1 Renewed Facility Operating License No. DPR-29 NRC Docket No. 50-254 10 CFR 50.73
Subject:
Licensee Event Report 254/2024-001-00 "Technical Specification 3.5.2 Action Not Performed Due to Inadequate Procedure Adherence" Enclosed is Licensee Event Report 254/2024-001-00 "Technical Specification 3.5.2 Action Not Performed Due to Inadequate Procedure Adherence," for Quad Cities Nuclear Power Station, Unit 1.
This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B) for an operation or condition which was prohibited by the plant's Technical Specifications.
There are no regulatory commitments contained in this letter.
Should you have any questions concerning this report, please contact Conner Bealer at 779-231-6207.
Doug Hild Site Vice President Quad Cities Nuclear Power Station cc:
Regional Administrator-NRC Region Ill NRC Senior Resident Inspector-Quad Cities Nuclear Power Station
Abstract
On November 22, 2024, it was discovered that an event that occurred on March 28, 2023, resulted in a condition that was prohibited by the plants' Technical Specifications (TS). Specifically, at approximately 0946 CDT on March 28, 2023, with Quad Cities Unit 1 at 0% power, when a scram was inserted to support Operations refueling outage activities. Inadequate procedure usage and adherence resulted in a Reactor Pressure Vessel Water Inventory Control (RPV WIC) related drainage event through control rod drive vent valves. (TS 3.5.2 requires either reasonable administrative controls, or ongoing calculations of drain time estimates and appropriate TS Actions. The applicability of TS 3.5.2 RPV WIC Condition E was not recognized; therefore, the associated Required Action was not performed.
The cause of the Unit 1 loss of RPV WIC inventory was due to failure to follow procedure. No equipment failed in this event.
Immediate actions included resetting the scram, effectively isolating the drain path, then subsequently closing the vent valves. Follow up corrective actions included human performance tool-usage reinforcement and operation procedure updates.
This report is being submitted under 10 CFR 50.73(a)(2)(i)(B) for an operation or condition which was prohibited by the plant's Technical Specifications.
PLANT AND SYSTEM IDENTIFICATION
- 2. DOCKET NUMBER YEAR 00254 2024 -
- 3. LE R NUMBER SEQUENTIAL NUMBER 001 REV NO.
00 General Electric - Boiling Water Reactor, 2957 Megawatts Thermal Rated Core Power.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
EVENT IDENTIFICATION Technical Specification 3.5.2 Action Not Performed Due to Inadequate Procedure Adherence
CONDITION PRIOR TO EVENT
Unit: 1 Reactor Mode: 5 Event Date: 03/28/2023 Mode Name: Refueling Event Time: 0946 CDT Power Level: 0%
No systems, structures, or components that were inoperable at the start of the event contributed to the event.
A. DESCRIPTION OF EVENT
On November 22, 2024, it was discovered that an event that occurred on March 28, 2023, resulted in a condition that was prohibited by the plant's Technical Specifications (TS). Specifically, at approximately 0946 CDT on March 28, 2023, with Quad Cities Unit 1 at 0% power, when a scram was inserted to support Operations refueling outage activities. Prior to the scram being inserted, the operation procedure directs opening the 1-0305-107 Control Rod Drive (CRD) accumulator vent valves [V] on each of the 177 Hydraulic Control Units (HCU)[HCU] to discharge the accumulators [ACC] to protect the Control Rod Drive Mechanism (CROM) mechanical seals. When performing the activity, the 1-0305-107 valves on each of the 177 HCUs, which the procedure directs to be re-closed after discharging to isolate the HCUs prior to the scram, were left open. This established a drain path from the Reactor Vessel through the CRDs and to the Reactor Building ground floor area, when the scram was inserted.
TS 3.5.2 describes requirements for Reactor Pressure Vessel (RPV) Water Inventory Control (WIC),
including those administrative controls required when potential drainage paths may be created during shutdown conditions. This TS requires the use of reasonable controls, such as approved procedures, to prevent loss of inventory during maintenance activities. When such reasonable controls are not available, manual calculations shall be performed to estimate the RPV drain down time, with specific actions required at different drain down time estimates.
The reasonable RPV WIC administrative controls provided in the operation procedure to verify valve positioning prior to inserting the scram were not properly implemented to prevent the temporary opening of the 1-0305-107 valves from causing a draining event. The inadequate procedure usage was unrecognized during the event, and was NRC identified following the event. Since Operations believed that reasonable administrative controls were properly in use at the time, no actions had been established to perform drain time calculations in accordance with TS Surveillance Requirement (SR) 3.5.2.1. Failure
- 2. DOCKET NUMBER
- 3. LE R NUMBER YEAR SEQUENTIAL REV NUMBER NO.
00254 2024 -
001 00 to perform either of these actions should have resulted in entry into TS 3.5.2 Condition E. The Required Action to immediately initiate action to restore drain time to ~ 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> was not completed at that time because the need to enter Condition E during the event was not recognized.
B. CAUSES OF EVENT The cause of the event is that Operators failed to properly apply fundamental behaviors in procedure use and adherence in the execution of the operation procedure. The procedure was not place-kept, nor were all the required physical actions taken in the field. The contributing causes are that both the enforcement of Human Performance (HU) and Technical Human Performance (THU) tool usage and the Pre-Job Brief conducted were inadequate to prepare and execute the activity correctly. Additionally, communication of field work completed between the Equipment Operators and Nuclear Station Operator was not sufficiently detailed to ensure aligned understanding of the actual work completed. The lack of required HU and THU behaviors and procedure use and adherence inadvertently eliminated the reasonable controls required to limit the RPV drain rate. In the absence of reasonable administrative controls, which were not provided because of the lack of Procedure Use and Adherence, the manual calculation of drain down times would have been required; however, this was not recognized at the time of the event. Operations personnel failed to perform the actions required by TS 3.5.2 RPV WIC, which resulted in an inadvertent entry into TS 3.5.2 Condition E for a drain time less than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This was NRC identified.
C. SAFETY ANALYSIS
SYSTEM DESIGN While in Reactor Refueling Mode, RPV WIC is required to protect the Reactor Vessel Water Level Safety Limit and the fuel cladding barrier to prevent the release of radioactive material to the environment should an unexpected draining event occur. The Safety Limit ensures that the reactor vessel water level is greater than the top of the active irradiated fuel in order to prevent elevated clad temperatures and resultant clad perforations. The Drain Time of the RPV water inventory to the Top of Active Fuel must remain greater than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, as it is the considered the reasonable time to identify and initiate action to mitigate unexpected draining of reactor coolant.
SAFETY ANALYSIS
There were no safety consequences as a result of this event. The operating crew responded correctly to the event. During the event, reactor water level dropped from its then steady-state level of about 184.5 inches to about 179 inches. The Low Flow Feedwater Regulating Valve opened during the event, recovering reactor water level. Top of Active Fuel is at -142 inches, therefore the lowest reactor water level recorded during the event remained 321 inches above Top of Active Fuel. At the time of the event, both loops of the Core Spray system were operable and available to supply makeup water if needed.
There was no equipment failure associated with this event. The event was within the analysis of UFSAR Chapter 15. There was not a radioactive release associated with the event. This event is not a Safety System Functional Failure (SSFF) per NEI 99-02.
D. CORRECTIVE ACTIONS
Immediate:
- 2. DOCKET NUMBER YEAR 00254 2024 -
- 3. LER NUMBER SEQUENTIAL NUMBER 001 REV NO.
00
- 1. At 0952 CDT on March 28, 2023, about six minutes after the initial scram was inserted, personnel in the main control room reset the scram. This effectively isolated the drain path from the reactor through the CRD HCUs and ended the event. All 1-0305-107 HCU Vent Valves were subsequently closed.
- 2. Contaminated RPV water on the reactor building ground level near the CRD HCUs was controlled and cleaned up by the site radiation protection department.
Follow up:
- 1. Human Performance and Procedure Use and Adherence practices were reinforced within the operations department and other site personnel. Actions included Human Performance (HU) Oral Boards, shift manager Paired Observations, and supplemental Operations leadership observations on discussion of HU and Technical Human Performance (THU).
- 2. Procedure QCOP 0500-04, Inserting Manual Scrams, was updated to include screening for Reactor Pressure Vessel Water Inventory Control applicability and add cautions to ensure valve positioning is verified prior to scram insertion.
E. PREVIOUS OCCURRENCES The station events database, LERs and INPO Industry Reporting Information System (ISIS) were reviewed for similar events at Quad Cities Nuclear Power Station. This event was caused by a human performance error of inadequate Procedure Use and Adherence resulting in an inadvertent loss of Reactor Vessel System Inventory. Based on the conditions of this event, cause and associated corrective actions, one event described below has been found to have a similar cause.
LER 2021-001-00 (05/18/2021) Automatic Initiation of Emergency Diesel Generator Due to Transformer Maintenance was found to be a similar event. The cause of the trip of the Unit 1 Reserve Auxiliary Transformer (RAT) and automatic initiation of Unit 1 EOG was a human performance error during performance of the Unit 1 RAT to Bus 12 relay routines. Workers failed to perform an adequate pre-job brief prior to work execution and failed to perform human performance verification techniques to validate the status of the Unit 1 RAT.
F. COMPONENT FAILURE DATA
No equipment failures are applicable. Page_4_ of _4_